At router communication

Hi , is there a way for a router to keep sending and processing data while making sure that when the other router sends its data it is ready to read it and resend it ?
Both routers are in at mode and already router 1 is sending data to the coordinator which is in api mode , when router 2 sends its data i wante router 1 to read it and send it to the coordinator and then continue what it was doing in the first place . Now i know that arduinos are linear but im sure there is a work around since that's the point of an xbee sensor network to be able to relay data . So if someone has an idea or a sample code that would be great .